This invention relates generally to position sensing and more particularly to capacitively sensing the postion of one mechanical part with respect to another.
There are many occasions when it is necessary to know the position of one mechanical part relative to another. For example, in a radial arm saw it is necessary to know the elevation of the saw blade with respect to a work table. Another example would be the relative position of the jaws of a pair of calipers. In fact, in the latter case, providing the relative position of the two mechanical parts is the entire function of the device. Many other examples could be given. Heretofore, such measurement has often been done mechanically. Mechanical measurement is subject to several errors, however, not the least of which are human operator error and mechanical wear of the measuring components. Electronic measuring devices in some respects eliminate these errors, but heretofore electronic measuring devices were not suitable for all measuring applications. Some electronic measuring devices could be too expensive, for example, for use in some consumer items, and/or they might suffer adversely from a harsh environment in which the measurement would be taken. An example is the measurement of various saw positions (elevation, bevel angle, mitre angle, etc.) in connection with powered saws such as table saws and radial arm saws. Particularly when these saws are to be used by the ordinary consumer, the cost of adequate electronic measuring devices can be prohibitive as well. It should also be appreciated that heretofore electronic position measuring devices have taken up considerable space and have involved a number of mechanical parts, neither of which is desirable in a consumer item.